Thermal circuit-breaker.



J. M. JOHNSON.

THERMAL CIRCUIT BREAKER.

APPLICATION nLEnJuLY 2, 1913.

1,179,107. Panted Apr. 11, 1916.-

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' l UNITED STATES PATENT OFFICE. vJOHN M. JoIINsoN, OE KANSAS cITY, KANSAS, AssIGNoR To THE uNITED sTATEsA AUTOMATIC EIRE ALARM coMrANY, A CORPORATION OE MISSOURI. f

THERMAL CIRCUIT-BREAKER.

Specification of Letters Patent.

` Patented Apr.' 11, 1916.

Application led July 2, 1913; Serial N o. 777,665.

Yand State of Kansas, have invented certain new and useful Improvements in' Thermal Circuit-Breakers, of which thefollowing'is a specification:

This invention relates to improvements in thermal circuit-breakers designed for use 'more particularly in lconnection with fire alarm apparatus where the circuit-breakers are located 1n places where a fire, 1f occurring, will cause a sulicient rise in temperature to operate one or more'of the circuitbreakers .before the fire can gain uncontrollable headway.

In order that the invention may be fully understood, reference will now'be made to the accompanying drawing forming a part of this specification, with the understanding, however, that while in the drawing there is shown a practical embodiment of the invention, thestructure illustrated is susceptible of changes and modications so long as the salient features ofthe invention are retained and the result'aimed at is obtained.

In the drawing: Figure l is a broken elevation partly in section of a circuit breaker constructed in accordance with my invention. Fig. 2 is a central vertical section on line II-II ofF ig. 1. Fig. 3 is an enlarged-broken section of .the upper portion of the circuit-breaker taken on the plane of line II-II of Fig. 1. Fig. 4 is a detail side elevation partly in section of certain elements employed invcarrying out the invention. Fig. 5 is an inverted plan view of the device. l Fig. 6 is a detail side elevation of a bell-shaped member and one of the circuit terminals carried thereby.

1 designates a basic member made, preferably, in the form of a ceiling rosette from insulated material, such, for instance as porcelain. Said basic member 1 has an extension 2, containing athreaded-socket 3 held l in said extension 2 by a conducting plate 4.

'5 designates a disk of insulating material arranged within the socket member 3 and,

abutting the conducting Vplate 4, A`against which it is held by a screw 6, extending into the basic member 1 and threaded into la sec.-

temperature. By

shaped element 9 is open at its large end and closed at its small end, which latter has affixed thereto a block of insulating material 12, incased in a Athreaded sleeve 13 adapted to be screwed into Ithe socket 3. Socket 3 and sleeve 13, are formed of conducting metal to constitute part of a path, hereinafter described, between the conducting plates 4 and 7.

One end of terminal 10, extends through the closed end of the bell-shaped element 9 and the block 12 from which latter it pro-n jects as disclosed by Fig. 3, to contact the screw 6. One end of the circuit terminal 11 passes through 'the closed end of the bellshaped element 9, bends backward through the block 12 and engages the metal' sleeve 13. The fre'e ends of the circuit terminals 10 and 11 are connected by a fusible element 14 inclosed in a glass lor othersuitable receptacle 115. Said/fusible element 14 consists, preferably, of an alloy of leady and mercury proportioned to melt at the desired y placing the fusible element 14 in the receptacle 15, said fusible element, on melting, falls in a body from the terminals 10 and 11 and thus insures .a clean breaking lof the circuit.

16 and 17 designate binding-screws .threaded into the conducting plates 4 and 7,

to receive the ends of wires 18 and 19, respectively, constituting partof a normally closed circuit, such, for instance as disclosed in my copendin-g application, led Oct.- 28,

V1912, Serial No. 728,097.

The basic member 1 is provided with a housing 20, to protect the glass lbell-shaped4 member 9 from breakage. Said houslng 20 "is securedvto the basic member 1,'by a setscrew 21, and is of a size and shape to inclose thebell-shaped element 9, the lower .end of which, like the lower end of said 'apron is left open, so that heated gases may freely circulate. around the fusible member 14.` The path of the current is through conducting plate 4,v socket 3, sleeve 13, terminal 11 fusible element 14, terminal 10, screw 6, and the conducting plate 7.

When used in connection with a fire-alarm system, the circuit-breakers are placed in any convenient position, usually at or near the ceiling of the room to be protected, so that heated air or gases of combustion arising from a fire will reach the fusible element and by melting the same break the circuit between the terminals l0 and 11 and there-` by transmit an alarm to a central or sub-station.

The devices can be made at small cost and of suicient accuracy for the purpose of the invention, or even should the fusible elements 14 vary a degree or two from accuracy, it is of no moment since they may be arranged to break the circuit at a temperature far below that of a re, and yet sufliciently above any temperature conditions to prevent the opening of the circuit except in the event of a fire, which latter event, if

quite distant from the circuit breakers, will cause the same to respond long before the fire can gain material headway.

Should a fire occur it may destroy some of the circuit-breakers even though the fire be put out before much damage is done, and under these circumstancessaid circuit-breakers are renewed with the greatest ease and at little cost, since it is only necessary to unscrew the sleeve 13 from the socket 3 and replace said sleeve with a new one containing the bell-shaped element 9, the terminals 10 and 11, and the fusible element 14 connect-I ing said terminals.

Having thus described my invention, what I claim and desire to secure `by Letters Patent is:

l. In a device of the character described,

a basic member, a threaded socket carried by said basic member, at plug screwed into said socket, a bell-shaped apron of insulating material open at one end and closed at` a basic member of insulating material, twoA v conductors separated from each other and secured to said basic member, a metal socket secured to said basic member and communicating with one of the conductors, a plug of insulating material having a metallic threaded sleeve removably-engaging said metal socket, two circuit terminals carried by but spaced apart by said plug, the end of one of said terminals contacting said sleeve and the end of the opposite terminal projecting from the plug, a screw engaging one of the conductors and adapted to be abutted by said projecting end of the circuitterminal when the sleeve is screwed into the plug, and fusible means electrically-connecting said circuit terminals.

In testimony whereof I aiiiX my signature, in the presence of two witnesses.

JOI-IN M. JOHNSON.

Witnesses: v

F. Gr. FISCHER, L. J. FISCHER. 

